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Questions and Answers
Which of the following statements is true regarding electron-withdrawing groups and carboxylic acids?
Which of the following statements is true regarding electron-withdrawing groups and carboxylic acids?
The acidity of halogen-substituted ethanoic acids decreases with the electronegativity of the substituent halogen.
The acidity of halogen-substituted ethanoic acids decreases with the electronegativity of the substituent halogen.
False
What are the effects of increasing the distance of the substituent group from the carboxyl group on acidity?
What are the effects of increasing the distance of the substituent group from the carboxyl group on acidity?
The acidity decreases.
The order of acidity for chloro-substituted ethanoic acids from highest to lowest acidity is ____.
The order of acidity for chloro-substituted ethanoic acids from highest to lowest acidity is ____.
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Match the following halogen substitutions with their respective pKa values:
Match the following halogen substitutions with their respective pKa values:
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What is the primary product formed when ethanoyl chloride reacts with water?
What is the primary product formed when ethanoyl chloride reacts with water?
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Chloroethane reacts vigorously with water to produce hydrochloric acid.
Chloroethane reacts vigorously with water to produce hydrochloric acid.
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Name one reagent used to produce ethanoyl chloride from ethanoic acid.
Name one reagent used to produce ethanoyl chloride from ethanoic acid.
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The reaction that produces ethanoic acid from ethanoyl chloride and water is called _____.
The reaction that produces ethanoic acid from ethanoyl chloride and water is called _____.
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Match the following compounds with their hydrolysis rate:
Match the following compounds with their hydrolysis rate:
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Which of the following statements about acyl chlorides is true?
Which of the following statements about acyl chlorides is true?
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The hydrolysis of acyl chlorides produces steamy white fumes due to the release of hydrogen chloride.
The hydrolysis of acyl chlorides produces steamy white fumes due to the release of hydrogen chloride.
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What is the product formed when ethanoyl chloride reacts with ethanol?
What is the product formed when ethanoyl chloride reacts with ethanol?
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What observation indicates a reaction between Ag+ and Cl- ions in solution?
What observation indicates a reaction between Ag+ and Cl- ions in solution?
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Primary amines react with acyl chlorides to produce amides.
Primary amines react with acyl chlorides to produce amides.
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What condition is required for the reaction of ethanoyl chloride with ammonia?
What condition is required for the reaction of ethanoyl chloride with ammonia?
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What property of acyl chlorides makes them very reactive?
What property of acyl chlorides makes them very reactive?
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The reaction between ethanoyl chloride and phenol requires __________.
The reaction between ethanoyl chloride and phenol requires __________.
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Aryl chlorides are more susceptible to nucleophilic attack than alkyl chlorides.
Aryl chlorides are more susceptible to nucleophilic attack than alkyl chlorides.
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What type of reaction occurs when ethanoyl chloride reacts with water?
What type of reaction occurs when ethanoyl chloride reacts with water?
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Match the following reactions with their appropriate conditions:
Match the following reactions with their appropriate conditions:
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The carbon atom in a C-Cl group carries a ______ partial positive charge than the carbon atom in a C=O group.
The carbon atom in a C-Cl group carries a ______ partial positive charge than the carbon atom in a C=O group.
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Which of the following is not a product of an acyl chloride reacting with an alcohol?
Which of the following is not a product of an acyl chloride reacting with an alcohol?
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The reaction between acyl chlorides and alcohols forms an equilibrium mixture.
The reaction between acyl chlorides and alcohols forms an equilibrium mixture.
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Match the following types of chlorides with their characteristics:
Match the following types of chlorides with their characteristics:
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What is produced when ethanoyl chloride reacts with concentrated ammonia?
What is produced when ethanoyl chloride reacts with concentrated ammonia?
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Which statement is true regarding the behavior of chloroethane?
Which statement is true regarding the behavior of chloroethane?
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The benzene ring enhances the reactivity of the carbon atom bonded to chlorine.
The benzene ring enhances the reactivity of the carbon atom bonded to chlorine.
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The reaction of acyl chlorides with alcohols produces ______.
The reaction of acyl chlorides with alcohols produces ______.
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What is the product formed when ethanoyl chloride reacts with ethylamine?
What is the product formed when ethanoyl chloride reacts with ethylamine?
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Carboxylic acids are stronger acids than alcohols and phenols.
Carboxylic acids are stronger acids than alcohols and phenols.
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What type of ions are formed when ethanoic acid dissolves in water?
What type of ions are formed when ethanoic acid dissolves in water?
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The acidity of carboxylic acids can be increased by __________ substituent groups.
The acidity of carboxylic acids can be increased by __________ substituent groups.
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Match the following carboxylic acids with their pKa values:
Match the following carboxylic acids with their pKa values:
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What effect do electron-donating groups have on the stability of carboxylate ions?
What effect do electron-donating groups have on the stability of carboxylate ions?
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The bond lengths of carbon-oxygen in a carboxylate ion are unequal.
The bond lengths of carbon-oxygen in a carboxylate ion are unequal.
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What is the Ka value of ethanoic acid at 25℃?
What is the Ka value of ethanoic acid at 25℃?
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Study Notes
Derivatives of Carboxylic Acids (A2)
- Acyl Chlorides: Derivatives of carboxylic acids, characterized by the acyl group (R-C=O) bonded to a chlorine atom (Cl).
- Examples: Ethanoyl chloride (CH₃COCl)
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Formation of Acyl Chlorides: Several methods exist for preparing acyl chlorides from carboxylic acids.
- Method 1: Reaction with phosphorus(V) chloride (PCl₅)
- Method 2: Reaction with sulfur dichloride (SOCl₂)
- Method 3: Reaction with phosphorus trichloride (PCl₃) (requires heating for reaction)
- Reactivity of Acyl Chlorides: Acyl chlorides are highly reactive compounds due to the presence of the electrophilic carbon atom in the carbonyl group (C=O).
- Structure and Bonding: The chlorine atom and the oxygen atom in the carbonyl group withdraw electrons from the carbon atom. The carbon atom has a partial positive charge, making it susceptible to attack by nucleophiles.
Hydrolysis of Acyl Chlorides
- Reagent: Water (H₂O)
- Conditions: Room temperature
- Products: Carboxylic acid and Hydrogen Chloride gas (HCl)
- Observations: Reaction is vigorous producing steamy white fumes due to HCl gas.
- Chemical Equation: CH₃COCl + H₂O → CH₃COOH + HCl
Ease of Hydrolysis
-
Order of Reactivity (highest to lowest):
- Acyl chlorides > alkyl chlorides > aryl chlorides (e.g., chlorobenzene)
- Acyl Chlorides: React rapidly with water due to high electronegativity of Cl and O atoms and positive charge on the carbon atom.
- Alkyl chlorides: React slowly with water
- Aryl chlorides (chlorobenzene): Do not react with water.
Explanation of Reactivity
- Nucleophilic Attack: The reactive carbon atom in the acyl chloride readily undergoes nucleophilic attack by water molecules or other nucleophiles.
- Electron Withdrawal: The high electronegativity of the chlorine atom and the oxygen atom pulls electrons away from the carbon atom, creating a partial positive charge, enhancing the susceptibility to nucleophilic attack.
- Intermediate Formation: The carbonyl group (C=O) and the chlorine atom facilitate the formation of an intermediate before a final product is created.
- Steric Hindrance: In alkyl chlorides/aryl chlorides, steric hindrance might hinder the attack by nucleophiles.
Reactions of Acyl Chlorides
- Alcohols: Reaction with alcohols produces esters and HCl.
- Phenols: Reaction with phenols also produces esters and HCl.
- Ammonia: Reaction with ammonia produces amides and ammonium chloride (NH₄Cl), producing white smoke.
- Primary Amines: Reaction with primary amines produces N-substituted amides and ammonium salts (e.g., ammonium chloride).
Acidity of Carboxylic Acids
- Weak Acids: Carboxylic acids are weak acids compared to stronger acids.
- Equilibrium: When dissolved in water, carboxylic acids are in equilibrium with their conjugate base (carboxylate ion).
- Dissociation Constant (Ka): Ethanoic acid (CH₃COOH) has a relatively small acid dissociation constant (Ka) value.
- Electronegativity: The electronegativity difference between the oxygen and the carbon in the carbonyl group helps to delocalize the charge. This stability makes the carboxylate form more favorable in an aqueous solution.
Relative Strength of Carboxylic Acids
- Substituent Effects: The strength of the carboxylic acid is affected by the substituent group on the carbon chain.
- Electron-Donating Groups: Electron-donating groups decrease the acid strength.
- Electron-Withdrawing Groups: Electron-withdrawing groups increase the acid strength.
- Distance and Size: The distance of the substituent group from the carboxyl group and also the size of the substituent group affects its acidity.
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Description
Explore the derivatives of carboxylic acids, particularly focusing on acyl chlorides. This quiz covers their formation, reactivity, and hydrolysis methods. Understand the key concepts through various preparation methods and the structural properties of these compounds.
